Insert, holder and post-treatment unit for exhaust gases

ABSTRACT

An insert ( 50 ) for a holder ( 22 ) in a post-treatment unit ( 10 ) for exhaust gases of a combustion engine, has a socket ( 52 ) for a treatment component ( 70 ) intended to have flowing through it the exhaust gases which are to be treated, a connector ( 54 ) for holding the insert ( 50 ) in position in the holder ( 22 ), and a seal ( 82 ) for gastight closure of the socket ( 52 ) relative to the holder ( 22 ). The seal includes a sealing ring ( 82 ) on the socket ( 52 ) for cooperation in self-centering seat engagement with an opposite sealing ring ( 84 ) in the holder.

TECHNICAL FIELD

The invention relates to an insert for a holder in a post-treatment unitfor exhaust gases of a combustion engine, comprising a socket for atreatment component intended to have flowing through it the exhaustgases which are to be treated, connecting means for holding the insertin position in the holder, and sealing means for gastight closure of thesocket relative to the holder. The invention relates also to a holderfor such an insert and a post-treatment unit provided with such aninsert.

BACKGROUND

To meet increasingly stringent emission requirements, vehiclemanufacturers have long resorted to exhaust post-treatment. Thistreatment is performed in various catalysts and filters which transformthe exhaust gases chemically or physically so that only a small amountof the undesirable substances can escape from the exhaust pipe. In aninsert of the kind indicated above the treatment component may be, forexample, an oxidation catalyst, an SCR (selective catalytic reduction)catalyst or a wall flow filter. For substrates with coatings used in thefilters and catalysts to perform their function, they often need to beextractable from the post-treatment unit/silencer for reconditioning,e.g. for cleaning, emptying of ash residues which cause largeback-pressures and possibly for replacement of the treatment components.A known seal for such an insert comprises a so-called V-seal. After eachextraction, such a seal needs to be replaced by a new seal, since itwill have become plastically deformed and will no longer be tight enoughwhen the insert is reconnected to the holder for the post-treatment unitto be able to meet the prevailing requirements with regard to exhaustemissions. Today's emission requirements often do not allow even anoccasional percentage of the exhaust gases to leak past the inserts inthe post-treatment unit.

SUMMARY OF THE INVENTION

An object of the invention is to propose an inset of the kind indicatedin the introduction which has an effective seal and is easy to removeand put back without needing to replace the seal.

This is achieved by the features indicated in the claims set out below.

According to a version of the invention, said sealing means comprises asealing ring on the socket to cooperate in self-centering seatengagement with an opposite sealing ring in the holder. Such a sealingarrangement, which may in principle be regarded as working like a valveseat seal, has great sealing performance and can be reinserted manytimes. The annular embodiment also makes the seal flexurally elastic inthe circumferential direction so that the, for example, conicalself-centering forces the rings to tight linear abutment against oneanother when the insert is connected to the holder.

The sealing rings are made of hard material, e.g. metal, particularlysteel, although ceramic material is also conceivable. The sealing ringsmay also be machined, e.g. turned or ground, to high surface finenessfor optimum sealing performance. The surface fineness may be such thatthe closure becomes tight enough to meet prevailing emissionrequirements, e.g. the current Euro 6.

The sealing ring may also be located in respective corner recesses ofthe socket and the holder.

The connection to hold the insert in position in the holder may comprisea threaded connection. Such a connection, possibly verified bymonitoring of tightening torque, is an easy way of achieving good andcorrect abutment force between the sealing rings.

The threaded connection may comprise an outside thread on the socket toengage with an inside thread on the holder. This makes it possible forthe insert to be fitted in the holder in a single operation.

An outer end of the socket may also have a recess situated at acircumference for a tool to fasten and release the connection.

Other features and advantages of the invention may be indicated by theclaims and the description set out below of embodiment examples.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an exhaust post-treatment unit which maybe provided with an insert according to the invention;

FIG. 2 is a side view, partly in section, of an insert according to theinvention sealingly connected to a holder for an exhaust post-treatmentunit;

FIG. 3 is a side view of an insert according to the invention partlyinserted in a holder of a schematically depicted exhaust post-treatmentunit;

FIG. 4 is a cross-sectional view on a larger scale, with portions cutaway, of a seal according to the invention between an insert and aholder of an exhaust post-treatment unit;

FIG. 5 is a perspective view in cross-section, with portions cut away,of a cover arrangement for an exhaust post-treatment unit;

FIG. 6 is a cross-sectional view on a larger scale, with portions cutaway, of a closure region between a cover arrangement and an exhaustpost-treatment unit;

FIG. 7 is a perspective view, with portions cut away, of a covertightener for a cover arrangement; and

FIG. 8 depicts schematically an example of a cover tightener with aneccentric clamping means.

The same reference numbers are used throughout the drawings to denoteitems with the same or similar functions.

DETAILED DESCRIPTION OF EMBODIMENT EXAMPLES

FIG. 1 depicts an exhaust post-treatment unit 10 for an undepictedcombustion engine, e.g. a diesel engine of, for example, a freightvehicle. The post-treatment unit 10 comprises in a known way a housing12 with inlet and outlet apertures not depicted in detail for theexhaust gases from the engine. The unit 10 may have one or moreinterchangeable inserts, e.g. the insert 50 represented by a broken linein FIG. 1, each comprising a treatment component containing a substratearranged to have the exhaust gases flowing through it, e.g. an oxidationcatalyst, an SCR catalyst or a wall flow filter.

As illustrated in FIG. 2, the insert 50 has a thin-walled sleeve 52 orso-called “sleeving pipe”, which is open at both ends and into which thesubstrate 70 is pushed and is then axially fixed by a pair of mutuallyopposite locking rings 72 which are themselves fixed by annularshoulders 74 formed at the mutually opposite ends of the sleeve 52. Thesubstrate 70 may also have radial support in the form of an inner sleeve76 made of a suitable, e.g. shock-absorbing or vibration-damping,material.

As partly schematically further depicted in FIG. 3, the insert 50 may beinserted in and removed from the post-treatment unit 10 through anaperture 16 with a cover 30 in the housing 12. More specifically, theinsert 50 may be pushed into and pulled out from a holder 22 integratedin an exhaust duct 20 which in an undepicted way is welded in positionin the housing 12. The other end of the sleeve 52 is further providedwith an outside thread 54 for engagement with an inside thread 24 of theholder 22 so that the insert 50 can be firmly connected in the duct 20.An axial outer flange 56 at the outer edge of the sleeve 52 may furtherhave a number of recesses 58 evenly distributed round the circumferenceto engage with an undepicted tool for pulling out and releasing theinsert 50 in the holder 22 of the duct 20.

As most clearly illustrated in FIG. 2, there is an annular seal 80between the inner end of the sleeve 52 and the holder 22. The annularseal 80 comprises a pair of sealing means in the form of sealing rings82, 84 which cooperate by substantially linear contact and are made of asuitable grade of steel. As most clearly illustrated in FIG. 4, thesealing rings 82, 84 may be located in, for example, respective suitablyshaped corner recesses of the sleeve 52 and the holder 22 and beconnected in the recesses by suitable joints 86, e.g. welded or solderedjoints or possibly some other tight form of joint such as binding agentcapable of withstanding the high temperatures from the exhaust gasesflowing past. The seal 80 is self-centering due to the fact that one,84′, of the sealing surfaces 82′, 84′ of the rings 82, 84 is conical, sothat the seal 80 works in principle like a seat valve when the sleeve 52of the insert 50 is screwed firmly into the holder 22 of the duct 20.The rings 82, 84 may of course also be of reverse configuration so thatthe conical surface is on the sealing ring 82 of the sleeve 52 (notdepicted). The cooperating sealing surfaces 82′, 84′ are with advantagealso machined, e.g. turned and where appropriate ground, to high surfacefineness in order further to improve the sealing performance.

Reverting to FIG. 1, it also depicts an openable cover arrangement 30for a circular access aperture 16 in a sheetmetal wall 14 of thesilencer/post-treatment unit 10. As illustrated in more detail in FIG.5, the arrangement 30 comprises a cover 32 with a cover tightener 40.The cover 32, like a lid for paint cans, is made of a piece ofsheetmetal, e.g. sheet steel, with a covering cover disc 34 which has acurvature v, and a suitably slightly conical elastic sealing flange 38intended to sealingly engage with an edge of the aperture 16 when thecover 30 is pressed into the aperture 16. In the example in FIG. 5, theedge of the aperture 16 is delineated by an inner flange 18 which maylikewise, but need not necessarily, be slightly conical. The edge of theaperture 16 need not necessarily consist of a flange 18 but may possiblyalso be a circular inner edge with a possibly rounded cross-section (notdepicted).

The cover tightener 40 can clamp the cover 32 in a fitted state asdepicted in FIG. 6. In this example the lock tightener 40 has asupporting frame comprising a pair of mutually crossing supportingmembers or supporting arms 42 with diametrically opposite angled ends 44which are firmly connected, e.g. welded or soldered, to the inside ofthe sealing flange 38. A clamping means in the form of a clamping screw46 with a locknut 48 is threadedly connected to the supporting arms 42in their crossing region. The free end of the screw 46 engages with thecurved cover disc 34 so that when the screw 46 is tightened its free endpresses against the central region of the cover disc 34 and reduces thecurvature. When the arrangement 30 is placed in the aperture 16 of thepost-treatment unit 10, approximately as depicted in FIG. 6, the sealingflange 38 will then be moved in the direction of the arrow from theposition represented by chain-dotted lines to the position representedby continuous lines, so that it is further clamped sealingly against theedge/flange 18 of the aperture 16. As further depicted in FIG. 6, eachsupporting arm 42 may if necessary have, for example, a curvedcross-section to prevent outward deflection of the supporting arm 42when the clamping screw 46 is tightened.

Many variations of cover and cover tightener are possible. As depictedin FIG. 7, the cover tightener 40 may for example take the form of asupporting disc made of a piece of sheetmetal with recesses whichdelineate a suitable number of radial supporting arms or spokes 42. FIG.8 depicts schematically a cover tightener 40 with a clamping means 90comprising an eccentric element 92 supported pivotably in an aperture inthe supporting frame 42 and manoeuvrable by means of a handle 94 toalter the curvature of the cover disc 34 between the respective statesrepresented by chain-dotted and continuous lines.

It is also conceivable for the cover disc to curve in the oppositedirection (i.e. inwards into the aperture) from that depicted in thedrawing and for the clamping device then to exert tensile force insteadof pressure on the cover disc (not depicted).

The description set out above is primarily intended to facilitatecomprehension and no unnecessary limitations of the invention are to beinferred therefrom. The modifications which will be obvious to oneskilled in the art from perusing the description may be effected withoutdeparting from the inventive concept or the scope of the claims set outbelow.

1. An insert (50) for a holder (22) in a post-treatment unit (10) forexhaust gases of a combustion engine, comprising a socket (52) for atreatment component (70) intended to have flowing through it the exhaustgases which are to be treated, connecting means (54) for holding theinsert (50) in position in the holder (22), and sealing means (82) forgastight closure of the socket (52) relative to the holder (22),characterised in that said sealing means (80) comprise a sealing ring(82) on the socket (52) for cooperation in self-centering seatengagement with an opposite sealing ring (84) in the holder.
 2. Aninsert according to claim 1, in which the sealing ring (82) is arrangedfor conical seat engagement with the opposite sealing ring (84).
 3. Aninsert according to claim 1 or 2, in which the sealing ring (82) is madeof metal, particularly steel.
 4. An insert according to any one of theforegoing claims, in which the sealing ring (82) is machined to suchhigh surface fineness that said closure becomes tight enough to meetprevailing emission requirements.
 5. An insert according to any one ofthe foregoing claims, in which the sealing ring (82) is located in acorner recess of the socket (52).
 6. An insert according to any one ofthe foregoing claims, in which said connecting means comprise a threadedconnection (24, 54).
 7. An inset according to claim 6, in which saidconnecting means comprise an outside thread (54) on the socket (52) forengagement with an inside thread (24) on the holder (22).
 8. An insertaccording to any one of the foregoing claims, in which an outer end ofthe socket (52) has a recess (58) situated at a circumference for a toolfor fastening and releasing the connection (54, 24).
 9. A holder (22)for an insert (50) according to any one of the foregoing claims for apost-treatment unit (10) for exhaust gases and provided with saidopposite sealing ring (84).
 10. A holder according to claim 9, in whichthe opposite sealing ring (84) is made of metal, particularly steel. 11.A holder according to claim 9 or 10, in which the opposite sealing ring(84) is machined to such high surface fineness that said closure becomestight enough to meet prevailing emission requirements.
 12. A holderaccording to any one of claims 9-11, in which the opposite sealing ring(84) is located in a corner recess of the holder (22).
 13. Apost-treatment unit (10) for exhaust gases provided with an insert (50)and/or holder (22) according to any one of the foregoing claims.